Over-speed shut-off mechanism for turbines and the like



E. TREIRAT Aug. 25, 1964 OVER-SPEED SHUT-OFF MECX IANISM FOR TURBINESAND THE LIKE Filed July 31, 1962 VENTOR Fig.4 .N

EDUARD TREIRAT BY E k 4 M 6374/ //T14\O;N:Y

United States Patent 3,145,970 OVER-SPEED SHUT-OFF MECHANISM FORTURBINES AND THE LIKE Eduard Treirat, Nutley, N.J., assignor toSpecialties pevelopment Corporation, Belleville, N.J., a corporatlon ofNew Jersey Filed July 31, 1962, Ser. No. 213,809 9 Claims. (Cl. 25359)The present invention relates to turbines and, more particularly, to amechanism for shutting-oil. the supply of operating fluid to the turbineand stopping the turbine in the event the turbine operates at anexcessive speed which indicates that the turbine is running away.

The present invention is primarily concerned with the operation ofturbines which are not manually supervised. Such turbines are utilizedon missiles and non-manned space craft for supplying auxiliary power andusually are controlled by a complex electronic system which functions tostart the turbine and to shut-off the turbine at a predetermined momentand when the turbine runs away. Since electronic systems are subjectedto rugged environmental condition, malfunctioning of such systems inpart or in their entirety is not uncommon. Thus, if the system losescontrol of an operating turbine, the turbine eventually will overspeedand burst to inflict damage to other systems and devices, whereby themissile or craft may be destroyed or may be put 01f its planned course.

Accordingly, an object of the present invention is to provide amechanical arrangement for shutting-off runaway turbines which operatesindependently of electrical or electronic speed control devices.

Another object is to provide such an arrangement which first shuts edthe supply of operating fluid to the turbine and then applies a brakingforce to stop rotation of the turbine rotor.

Another object is to provide an overspeed valve control arrangement.

A further object is to provide such an arrangement which is simple,practical and economical in construction, and is reliable in operation.I

Other and further objects of the invention will be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claims, and various advantages notreferred to herein will occur to one skilled in the art upon employmentof the invention in practice.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description, and is shown in the accompanying drawing,forming a part of the specification, wherein:

FIG. 1 is a schematic side elevational view of a turbine equipped withmechanism in accordance with the present invention.

FIG. 2 is an enlarged fragmentary sectional view taken along the line 22on FIG. 1, illustrating the elements of the mechanism in their positionwhile the turbine is functioning normally.

FIG. 3 is a view similar to FIG. 2 illustrating the elements in theirposition after the turbine has attempted to run away and has been shut011?.

FIG. 4 is an enlarged sectional view, taken along the line 4-4 on FIG. 2with the shut-off valve and its operating member being shown in brokenlines in their actuated position.

3,145,970 Patented Aug. 25, 1964 Referring now to FIG. 1 of the drawingin detail, there is shown a fluid pressure medium operated turbine 10which generally comprises a casing section 11 for housing a turbinerotor 12 an annular casing section 14 at one side of the casing section11 and concentric therewith for housing a drum 15 rotatable with therotor 12, a turbine drive shaft 16 having the rotor secured thereon, anda valve 17 on the casing section 14 for controlling the flow of pressuremedium to the turbine.

As shown in FIGS. 2, 3 and 4, the valve 17 generally comprises a housing18 having an inlet 19 and an outlet 20 normally in fluid flowcommunication with the inlet and with a nozzle (not shown) in the rotorcasing section for supplying the medium for driving the rotor 12, avalve member 21 for shutting off flow communication between the inletand the outlet, and a member 22 for operating the valve member 21.

The valve member 21 preferably is a flapper pivotally mounted at 24 andpositioned adjacent the valve outlet 20 to overlie the same and to beengaged by the valve operating member 22. The valve operating member hasa. head 25 for engaging'the underside of the flapper and has a stem 26slidably mounted in a bore 27 extending through the valve housing 18 andradially into the casing section 14. In order to retain the flapper inits normal position (FIG. 2), the flapper and its operating member areprovided with coacting means for releasably locking the flapper on thevalve operating member. Such means may be a tab 28 on the flapper and arecess 29 in the head 25 of the valve operating member 22 for receivingthe tab 28.

The mechanism for actuating the valve operating member 21 includes ahollow drum 30 mounted for rotation in the casing section 14 and havingan annular inner wall 31, an arrangement 32 for normally preventingrotation of the hollow drum, and the drum 15 mounted for rotation withinthe hollow drum. The drum 15 has an annular outer wall 34 in closeproximity to the inner wall 31 of the drum 313 with sufiicient clearancebetween the walls 31 and 34 for free rotary movement of the outer wall34 with respect to the inner wall 31 under normal conditions. As shownherein, the drum may be formed integral with the rotor 12. The drum 15is so constructed and dimensioned that when the rotor 12 and the drum 15thereon are driven at an excessive speed the outer wall 34 is expandeddue to yielding of the drum material in response to centrifugal force tocause the outer wall 35 to engage the inner wall 31 and exert a forcethereon tending to rotate the drum 30 and to render the arrangement 32ineffective. The drum 15 may be solid or hollow as shown and may beslotted at its outer wall 34 to make the peripheral portion moreyieldable at a predetermined speed.

The arrangement 32 includes a hollow shear pin 35 having its inner enddisposed in a radially extending bore 36 of the drum 30 in radialalignment with the bore 27 and having its outer end disposed in the bore27 of the casing section 14 and in contact with the stem 26 of the valveoperating member 21, and a cam 37 on the outer surface of the hollowdrum for shearing the pin 35 upon rotation of the hollow drum 30 withthe drum 15. Preferably, the outer end of the shear pin 35 is fittedinto a bore 33 at the inner end of the stem 26.

The outer portion of the cam 37 is movable in an areaate recess 38 ofthe casing section 14 and the inner portion of the cam 37 is mounted inan arcuate recess 39 of the drum 30 which faces the recess 38, and thebores 27 and 36 are located between the ends of the recesses 38 and 39.The trailing end of the cam 37 is engaged by the trailing end of therecess 39 to be driven by the drum 30 and the leading edge of the camengages the shear pin 35. The outer leading surface 40 of the cam isinclined to effect radially outward movement of the valve operatingmember 22 when the pin is sheared, and the cam moves in a clockwisedirection as viewed in FIGS. 2 and 3.

In order to limit the rotary movement of the drum 30 within the casingsection 14, stop means are provided which include a circumferentiallyextending slot 41 in the drum 30, and one or more fixed pins 42projecting inwardly from the casing section 14. The pin 42 normally isat the leading end of the slot 41 and is adapted to be engaged by thetrailing end of the slot 41 to stop rotary movement of the drum 30. Forexample, the pin and the slot may be arranged to limit rotary movementof the drum 30 to about In operation, the elements of the controlmechanism are normally positioned and arranged as shown in FIG. 2 andFIG. 4 in full lines. Upon over-speeding of the turbine for example at130% normal speed, the outer wall 34 of the drum is caused to engage theinner wall 31 of the drum 3%), whereby the drum is rotated to cause thecam 37 to shear the pin and actuate the valve member 21 to shut off thesupply of pressure medium to the turbine as shown in FIG. 3 and in FIG.4 in broken lines. Since the drum 30 is now held against furtherrotation by the pin 42, the inner wall 31 of the drum 30 applies abraking force on the outer wall 34 of the drum 15 to gradually stoprotation of the turbine rotor 12 From the foregoing description, it willbe seen that the present invention provides a completely mechanicalarrangement for preventing the over-speeding of turbines whicharrangement is simple, practical and economical in construction andreliable in operation.

As various changes may be made in the form, construction and arrangementof the parts herein, without departing from the spirit and scope of theinvention and without sacrificing any of its advantages, it is to beunderstood that all matter herein is to be interpreted as illustrativeand not in any limiting sense.

I claim:

1. In a fluid pressure medium operated turbine, the combination of acasing section for housing a turbine rotor; a concentric annular casingsection at one side of said rotor casing section; a valve on saidannular casing section including an inlet and an outlet in fluid flowcommunication with said inlet and said rotor casing section, a valvemember for shutting olf flow communication between said inlet and saidoutlet, and a radially extending slidable member for operating saidvalve member; a hollow drum mounted for rotation in said annular casingsection and having an annular inner wall; a radially extending shear pinhaving an outer end adjacent the mner end of said valve operating memberfor normally preventing rotation of said hollow drum; a turbine rotor insaid rotor casing section driven by medium supplied through said valveoutlet; a second drum mounted within said hollow drum and connected forrotation with said rotor and having an annular outer wall in closeproximity to said inner wall with suflicient clearance therebetween forfree rotary movement of said outer wall with respect to said inner wall,said second drum being so constructed and dimensioned that when saidrotor is driven at an excessive speed said outer wall is expanded tocause said outer wall to engage said inner wall and exert a forcethereon tending to rotate said hollow drum; and a circumferentiallyextending cam on the outer periphery of said hollow drum for shearingsaid shear pin and for effecting actuation of said valve operatingmember by displacement of the outer end portion of said shear pin uponrotation of said hollow drum to position said valve member to shut offthe supply of medium through said valve outlet and to said rotor.

2. In a turbine according to claim 1, including stop means for limitingthe extent of rotation of said hollow drum, whereby engagement betweensaid inner and outer walls, when movement of said hollow drum isstopped, provides braking means for said rotor and said cam ispositioned to maintain said valve in closed position.

3. A turbine according to claim 2, wherein said hollow drum has acircumferential slot therein and said stop means is a pin projectinginwardly from said annular casing section which is normally at theleading end of said slot and is adapted to be engaged by the trailingend of said slot to limit rotation of said hollow drum.

4. A turbine according to claim 3, wherein said pin and slot arearranged to limit rotation of said hollow drum to about 10.

5. A turbine according to claim 1, wherein the outer wall of said hollowdrum and the inner wall of said annular casing section each have acircumferentially extending recess opposite the other, said hollow drumand said annular casing section each have a radially extending borealigned with the other and located between the ends of said recesses forrespectively receiving said shear pin and said valve operating member,and the trailing end of said cam is engaged by the trailing end of saidhollow drum recess and the leading end of said cam engages said shearpin.

6. In a fluid pressure medium operated turbine, the combination of acasing section for housing a turbine rotor; a concentric annular casingsection at one side of said rotor casing section; a valve on saidannular casing section including an inlet and an outlet in fluid flowcommunication with said inlet and said rotor casing section, a valvemember for shutting off flow communication between said inlet and saidoutlet, and a member for operating said valve member; a hollow drummounted for rotation in said annular casing section and having anannular inner Wall; means for normally preventing rotation of saidhollow drum; a turbine rotor in said rotor casing section driven bymedium supplied through said valve outlet; a second drum mounted withinsaid hollow drum and connected for rotation with said rotor and havingan annular outer wall in close proximity to said inner wall withsuflicient clearance therebetween for free rotary movement of said outerwall with respect to said inner wall, said second drum being soconstructed and dimensioned that when said rotor is driven at anexcessive speed said outer wall is expanded to cause said outer wall toengage said inner wall and exert a force thereon tending to rotate saidhollow drum; and means on said hollow drum for rendering said rotationpreventing means ineffective and for actuating said valve operatingmember upon rotation of said hollow drum to shut off the supply ofmedium to said rotor, said valve member being a pivotally mountedflapper positioned adjacent said valve outlet and to be engaged by saidvalve operating member, and said valve operating memher beingconstructed and arranged to move said flapper to overlie and close saidvalve outlet at the upstream side thereof and to retain said flapper insuch position upon operation thereof.

7. A turbine according to claim 6, wherein said valve operating memberand said flapper have coacting means for releasably locking said flapperon said valve operating member before actuation of said valve operatingmember.

8. A controlmechanism comprising an annular casing section, a valve onsaid casing section normally in one position, a hollow drum mounted forrotation in said annular casing section and having an annular innerwall, a radially extending shear pin having an outer end adjacent saidvalve for normally preventing rotation of said hollow drum with respectto said casing, a second drum mounted in said hollow drum for rotationby power driven means and having an annular outer wall in closeproximity to said inner wall with suflicient clearance therebetween forfree rotary movement of said outer wall with respect to said inner wall,said second drum being so constructed and dimensioned that when the sameis rotated at an excessive speed said outer wall is expanded to causesaid outer wall to engage said inner wall and exert a force thereontending to rotate said hollow drum, and a circumferentially extendingcam on the outer periphery of said hollow drum for shearing said shearpin and for actuating said valve by displacement of the outer end ofsaid shear pin upon rotation of said hollow drum to move said valve intoanother position.

9. Mechanism according to claim 8, including stop means for limiting theextent of rotation of said hollow drum, whereby engagement between saidinner and outer walls provides braking means for said second drum andsaid cam is positioned to maintain said valve in closed position.

References Cited in the file of this patent UNITED STATES PATENTS

1. IN A FLUID PRESSURE MEDIUM OPERATED TURBINE, THE COMBINATION OF A CASING SECTION FOR HOUSING A TURBINE ROTOR; A CONCENTRIC ANNULAR CASING SECTION AT ONE SIDE OF SAID ROTOR CASING SECTION; A VALVE ON SAID ANNULAR CASING SECTION INCLUDING AN INLET AND AN OUTLET IN FLUID FLOW COMMUNICATION WITH SAID INLET AND SAID ROTOR CASING SECTION, A VALVE MEMBER FOR SHUTTING OFF FLOW COMMUNICATION BETWEEN SAID INLET AND SAID OUTLET, AND A RADIALLY EXTENDING SLIDABLE MEMBER FOR OPERATING SAID VALVE MEMBER; A HOLLOW DRUM MOUNTED FOR ROTATION IN SAID ANNULAR CASING SECTION AND HAVING AN ANNULAR INNER WALL; A RADIALLY EXTENDING SHEAR PIN HAVING AN OUTER END ADJACENT THE INNER END OF SAID VALVE OPERATING MEMBER FOR NORMALLY PREVENTING ROTATION OF SAID HOLLOW DRUM; A TURBINE ROTOR IN SAID ROTOR CASING SECTION DRIVEN BY MEDIUM SUPPLIED THROUGH SAID VALVE OUTLET; A SECOND DRUM MOUNTED WITHIN SAID HOLLOW DRUM AND CONNECTED FOR ROTATION WITH SAID ROTOR AND HAVING AN ANNULAR OUTER WALL IN CLOSE PROXIMITY TO SAID INNER WALL WITH SUFFICIENT CLEARANCE THEREBETWEEN FOR FREE ROTARY MOVEMENT OF SAID OUTER WALL WITH RESPECT TO SAID INNER WALL, SAID SECOND DRUM BEING SO CONSTRUCTED AND DIMENSIONED THAT WHEN SAID ROTOR IS DRIVEN AT AN EXCESSIVE SPEED SAID OUTER WALL IS EXPANDED TO CAUSE SAID OUTER WALL TO ENGAGE SAID INNER WALL AND EXERT A FORCE THEREON TENDING TO ROTATE SAID HOLLOW DRUM; AND A CIRCUMFERENTIALLY EXTENDING CAM ON THE OUTER PERIPHERY OF SAID HOLLOW DRUM FOR SHEARING SAID SHEAR PIN AND FOR EFFECTING ACTUATION OF SAID VALVE OPERATING MEMBER BY DISPLACEMENT OF THE OUTER END PORTION OF SAID SHEAR PIN UPON ROTATION OF SAID HOLLOW DRUM TO POSITION SAID VALVE MEMBER TO SHUT OFF THE SUPPLY OF MEDIUM THROUGH SAID VALVE OUTLET AND TO SAID ROTOR. 